Printed boards are used within telecommunications systems and boards of this kind contain electrical conductors or wires that have been run or arranged by using layers of electrically-conducting foil and by arranging a number of foils above eachother, each foil separated by an intermediate layer of electrically-insulating foil, and by arranging required connections between the electrical foils.
When discrete components are mounted on one or both sides of such a printed board, then such an arrangement is called a printed board assembly.
However, in the description that follows we have used the term "printed board" to apply to both categories.
Printed boards of this kind, and for the application described above, require an electrical interaction with each other and therefore several printed boards are mechanically supported by a magazine. By means of electrical conductors via a back plane of the magazine said printed boards may electrically be interacted or interconnected with one another.
The printed boards are equipped with edge-related connectors or contact means, and the back plane of the magazine is equipped with corresponding connectors or contact means.
The connectors that belong to the printed boards are arranged to be able to interact with connectors that belong to the magazine. These connectors are coordinated in rows to the back plane.
Ordinarily, the back plane for magazines of this kind supports only required electrical conductors; that is the conductors that are required to connect the printed boards functionally to one another.
It is a known practice to use a rack arrangement that is designed to be able to hold several magazines, ordinarily positioned above one another, at a vertical distance from one another.
Rack arrangements, of the kind described above, have existed in numerous different embodiments. A common feature for one category of these rack arrangements is that the magazines can, via guides, be horizontally displaced from a fully-inserted position in the rack to a position that projects beyond the rack, and vice versa, thereby making the printed boards or the printed board assemblies that belong to the magazine more accessible for inspection or for replacement.
One or more printed boards might be replaced partly when a printed board malfunctions partly when the function has been modified in a way that requires a new printed board.
It is common for rack arrangements of this kind to interact with several magazines, each of which is equipped with a fixed back plane that has connectors positioned in columns or rows, and where the back plane in addition thereto is equipped with required bus arrangements and other electrical conductors or wires.
As an example of the prior art, we refer to the Patent Publication U.S. Pat. No. 4,871,324, which shows and describes a back plane with several connectors that were arranged in parallel columns, one beside the other.
Another known practice involves arranging "flexible" back planes.
As an example of the prior art, we refer to the content of the Patent Publication U.S. Pat. No. 5,325,270, which shows a flexible back plane arrangement that uses removable back plane modules that were mounted on a platform that enabled the back plane modules to be removed and exchanged with other types of circuit modules.
In this publication it shows that the magazine (10) has two contact groups (20U, 20L), in which the conductors or wires of one group (20U) are fixed, whereas the second group, the lower group (20L), makes up by a part of a detachable back plane module (22).
The back plane module (22) may glide in relation to a track (44).
The Patent Publication U.S. Pat. No. 5,234,348 also shows a back plane for interacting with several electronic components, where the back plane is inserted into a rack, that may be installed onboard a vehicle; for example an aeroplane.
Here is shown a detachable frame to which electronic components are mounted. Without having to dismount the rack from the vehicle, one simply removes the frame to obtain complete access to the back plane and connections for various components.
The contents of the following publications also relate to the background art: DE-C3-3 608 046; U.S. Pat. No. 2,857,558; DE-A-2 209 858; and SU-A1-1 299 568.